diff --git a/tc/m_nat.c b/tc/m_nat.c
index da947aea..0ec3fd11 100644
--- a/tc/m_nat.c
+++ b/tc/m_nat.c
@@ -156,7 +156,7 @@ print_nat(const struct action_util *au, FILE * f, struct rtattr *arg)
 	}
 	sel = RTA_DATA(tb[TCA_NAT_PARMS]);
 
-	len = ffs(sel->mask);
+	len = ffs(ntohl(sel->mask));
 	len = len ? 33 - len : 0;
 
 	print_string(PRINT_ANY, "direction", "%s",